1. Field of the Invention
This invention generally relates to computer component mounting systems, and more particularly to a retention mechanism for a removable electronic card for a computer system, such as a peripheral component interconnect (PCI) card. In one embodiment, the retention mechanism may allow a PCI card to be securely installed into a running computer system.
2. Description of the Related Art
A computer system may use removable electronic cards to contain subsystems or other assemblies that form part of the operating hardware of the system. For example, graphics cards, modems, audio cards, and other PCI cards may be plugged into a system to add functionality to the computer system. Removable electronic cards may allow a user to tailor a computer system to meet specific needs.
A card may function as a hardware interface between a computer system processor and a peripheral device. Peripheral devices may include, but are not limited to video displays, printers, disks, and networks. Generally, a card includes a circuit board and an endplate. The circuit board may have a connector that has a number of electrical contacts. The connector may be adapted to fit within a socket that is electrically coupled to a circuit board of the computer system. The circuit board may be electrically connected to the computer system processor. The endplate of the card may be used to secure the card to the chassis of the computer system. The endplate and the computer system sheet metal adjacent to the endplate may form part of an electro-magnetic interference (EMI) seal for the computer system. The endplate may have a number of device connectors that allow cables or connection systems to electrically couple the peripheral device to the computer system.
A computer system typically has several sockets adapted to mate with the electrical contacts of a card. When a card is not installed in a socket, a blanking cover may be used to cover the opening in a computer system enclosure where the endplate of a card would be positioned. The blanking cover may function as a computer system safety precaution to prevent the insertion of foreign material into the computer system. The blanking cover may also serve as part of the EMI seal for the computer system. The shape of a blanking cover typically resembles the shape of an endplate of a card.
The endplate of a card may be used to attach a card to a computer system chassis. The endplate of the card may have a tongue at one end and a tab at the other end. The tab is typically perpendicular to the tongue, and the tab may have a hole or slot. The tongue may fit within a tongue slot on the computer chassis. When the tongue is placed in the tongue slot, the hole or slot on the tab aligns with a hole in the chassis. A fastener, such as a small screw, may be inserted through the hole or slot and into the computer chassis to secure the endplate to the computer system chassis. Securing the endplate to the computer system chassis inhibits the contacts of the card from becoming disengaged from the socket on the circuit board.
A common problem with retaining a card within a computer system using a fastener is that handling the fastener may be difficult. Typically, the fastener used to secure a card endplate to the computer chassis is a small screw. Handling a small screw can be difficult, especially in the tight confines of a computer enclosure. Alternate systems for attaching blanking covers and PCI cards to a computer system are shown in U.S. Pat. No. 5,640,309 issued to Carney et al.; U.S. Pat. No. 5,673,175 issued to Carney et al.; and U.S. Pat. No. 5,748,453 issued to Carney et al. (all three of these patents are incorporated by reference as if fully set forth herein).
A trend in the computer industry is to have cards that may be installed in a computer system while the computer system is running. A xe2x80x9chot pluggable cardxe2x80x9d is a card that may be installed in a computer system while the computer system is running. The development of hot pluggable cards has led to the need to develop a card retention mechanism that generally does not use separate component fasteners to hold cards in place. A retention mechanism that generally does not use separate fasteners is needed due to the possibility that a user might drop a separate component fastener into the computer system during installation or removal of a card. Dropping a fastener into an operating computer system could damage the computer system.
An embodiment of a card retention mechanism may securely hold an electronic card or blanking cover within a computer system. Retention mechanism embodiments may securely hold cards or blanking covers to a chassis of the computer system. A card retention mechanism may include a carrier and at least one retainer. The carrier may mount to a chassis of a computer system. The carrier may be positioned near openings in the chassis that accommodate blanking covers or card endplates. Retainers may be rotatably mounted to the carrier. Preferably, the carrier holds one retainer for each blanking cover or endplate opening in the chassis.
When a retainer holds a card within a card slot, the retainer may be locked in a closed position. In the closed position, the side projections of the retainer may engage rotation inhibiting surfaces on the carrier to prevent the retainer from rotating to an open position. When a user desires to remove a blanking cover or card, the retainer may be gripped, the side projections may be withdrawn so that the side projections do not contact the rotation inhibiting surfaces, and the retainer may be rotated away from the blanking cover or card.
When the retainer does not engage a blanking cover or endplate, the retainer may engage a rotation stop to hold the retainer in an open position. When the retainer is held in an open position by the rotation stop, the retainer will generally not interfere with the installation, maintenance, or removal of blanking covers or cards.
An advantage of retention mechanism embodiments is that the retention mechanisms may reduce or eliminate the need for separate component fasteners to secure cards or blanking covers to a computer system. Retention mechanism embodiments may be used in conjunction with other fasteners in particular systems. Another advantage of retention mechanism embodiments is that the retention mechanisms do not interfere with EMI seals formed between the chassis of the computer system and the card endplates or blanking covers. Another advantage of retention mechanism embodiments is that retainers of the retention mechanisms may be held in open positions so that the retainers do not interfere with installation, maintenance or removal of cards or blanking covers. Another advantage of retention mechanism embodiments is that the mechanisms will inhibit connectors of cards from becoming disengaged from circuit board sockets during use.
When the card is a PCI card installed in a computer system, attaching a peripheral device to the computer system may subject the card and the computer system to significant forces. The forces may be applied during attachment and removal of cables, or other types of connectors, into the card endplate. The forces applied to the endplate and the computer system must be resisted so that the card is held securely in place. An advantage of retention mechanism embodiments is that the mechanisms are sturdy and can withstand forces applied to the endplates while still securely holding cards within the computer system. Retention mechanism embodiments are able to hold cards securely in place, maintain the EMI seal between the chassis and the endplate, and prevent the contacts of the cards from being uncoupled from circuit board sockets during use.
Another advantage of retention mechanism embodiments is that different colors may be used for different components of the mechanisms. The different component colors may help a user who has never seen or used a retention mechanism to intuitively use the retention mechanism properly. Other advantages of retention mechanism embodiments may include that the retention mechanisms are durable, light weight, simple, efficient, reliable and inexpensive; yet the retention mechanisms may also be easy to manufacture, install, maintain and use.